Efficient synthesis of β’-amino-α,β-unsaturated ketones

• Isabelle Abrunhosa-Thomas,
• Aurélie Plas,
• Nishanth Kandepedu,
• Pierre Chalard and
• Yves Troin

Beilstein J. Org. Chem. 2013, 9, 486–495, doi:10.3762/bjoc.9.52

• nucleophilic addition reaction of Grignard reagents to N-carbamoyl β-amino Weinreb amides (Scheme 2) [18]. Conjugate addition of (R)-N-benzyl-N-methylbenzylamide to methyl cinnamate under basic conditions led to β–aminoester 5 with high diastereoselectivity (dr >94%) [11][12]. Subsequent transformation of the

New simple synthesis of ring-fused 4-alkyl-4H-3,1-benzothiazine-2-thiones: Direct formation from carbon disulfide and (E)-3-(2-aminoaryl)acrylates or (E)-3-(2-aminoaryl)acrylonitriles

• Qiuping Ding,
• Yuqing Lin,
• Guangni Ding,
• Fumin Liao,
• Xiaoyan Sang and
• Yi-Yuan Peng

Beilstein J. Org. Chem. 2013, 9, 460–466, doi:10.3762/bjoc.9.49

• expected to construct 4-alkyl-4H-3,1-benzothiazine-2-thione derivatives through a one-pot base-promoted intermolecular addition/intramolecular Michael addition reaction. Results and Discussion In our initial study, we examined the tandem reaction with various bases and solvents to optimize the reaction

Recent advances in transition-metal-catalyzed intermolecular carbomagnesiation and carbozincation

• Kei Murakami and
• Hideki Yorimitsu

Beilstein J. Org. Chem. 2013, 9, 278–302, doi:10.3762/bjoc.9.34

• ][139][140][141][142][143]. Manganese-catalyzed regioselective allylmetalation of allenes was reported (Scheme 53) [144]. The regioselectivity of the manganese-catalyzed addition reaction was opposite to that of the rhodium-catalyzed reactions, and vinylmagnesium intermediates were formed. Although

A new synthetic protocol for coumarin amino acid

• Xinyi Xu,
• Xiaosong Hu and
• Jiangyun Wang

Beilstein J. Org. Chem. 2013, 9, 254–259, doi:10.3762/bjoc.9.30

• experimental results, DBU is the best base among the three, and the reaction can be carried out at room temperature to obtain a relatively good yield. Alkylation of DEAM is widely used to synthesize α-amino acids [13], which was also applied here to prepare the coumarin amino acids. Through Michael addition

• reaction of DEAM to terminal alkene 5, malonate 6 was formed in high yield, and it was followed by the total hydrolysis of compound 6 with concentrated aqueous HCl solution to afford the coumarin amino acid 1. We found that the hydrolysis needed a high concentration of aqueous HCl solution (12 M) and a

Thioester derivatives of the natural product psammaplin A as potent histone deacetylase inhibitors

• Matthias G. J. Baud,
• Thomas Leiser,
• Vanessa Petrucci,
• Mekala Gunaratnam,
• Stephen Neidle,
• Franz-Josef Meyer-Almes and
• Matthew J. Fuchter

Beilstein J. Org. Chem. 2013, 9, 81–88, doi:10.3762/bjoc.9.11

• could potentially be responsible for thioester hydrolysis. We prepared and used synthetic probe 10 [30] (Scheme 3) in order to test this hypothesis. Coumarin-based probe 10 is known to react extremely fast with thiols through a Michael addition reaction. While the fluorescence of 10 is efficiently

The chemistry of bisallenes

• Henning Hopf and
• Georgios Markopoulos

Beilstein J. Org. Chem. 2012, 8, 1936–1998, doi:10.3762/bjoc.8.225

Facile synthesis of functionalized tetrahydroquinolines via domino Povarov reactions of arylamines, methyl propiolate and aromatic aldehydes

• Jing Sun,
• Hong Gao,
• Qun Wu and
• Chao-Guo Yan

Beilstein J. Org. Chem. 2012, 8, 1839–1843, doi:10.3762/bjoc.8.211

• aryl amines could be used in the reaction to give more polysubstituted tetrahydroquinolines. Thus, after the addition reaction of one kind of arylamine with methyl propiolate had been completed, the aromatic aldehyde and the second arylamine were introduced to the reaction system. By using this method

Automated three-component synthesis of a library of γ-lactams

• Erik Fenster,
• David Hill,
• Oliver Reiser and
• Jeffrey Aubé

Beilstein J. Org. Chem. 2012, 8, 1804–1813, doi:10.3762/bjoc.8.206

• protocol, we explored the use of various chiral amines in the conjugate addition reaction of propionaldehyde (2{1}) to N-phenylmaleimide (1{1}) (Table 1). Although the achiral pyrrolidine was found to be an efficient catalyst in the reaction [12], this led to a ~1:1 mixture of racemic succinimide

• reductive amination/lactamization reaction was performed in methylene chloride [12]. However, in order to combine this step with the previous Michael addition step, we thought to perform the reaction in chloroform (Scheme 3). In fact, when the Michael addition reaction between propionaldehyde (2{1}) and N

Organocatalytic tandem Michael addition reactions: A powerful access to the enantioselective synthesis of functionalized chromenes, thiochromenes and 1,2-dihydroquinolines

• Chittaranjan Bhanja,
• Satyaban Jena,
• Sabita Nayak and
• Seetaram Mohapatra

Beilstein J. Org. Chem. 2012, 8, 1668–1694, doi:10.3762/bjoc.8.191

• -unsaturated ketones have also responded as Michael acceptors in the organocatalytic tandem Michael addition reaction towards the synthesis of tetrahydroxanthones. Córdova et al. [50], in 2007, reported the first organocatalytic asymmetric synthesis of tetrahydroxanthenones through the domino Michael–aldol

• , and the power of tandem/domino/cascade-Michael addition reactions promoted by chiral organocatalysts has been intensely studied within this field. In this review, we have outlined some significant works concerning the organocatalytic enantioselective Michael addition reaction from three different

Arylglycine-derivative synthesis via oxidative sp³ C–H functionalization of α-amino esters

• Zhanwei Xu,
• Xiaoqiang Yu,
• Xiujuan Feng and
• Ming Bao

Beilstein J. Org. Chem. 2012, 8, 1564–1568, doi:10.3762/bjoc.8.178

• arylglycine derivatives has attracted considerable attention. Over the past years, many methods have been developed for the preparation of arylglycine derivatives [3]. Among these, the addition reaction of a carbon nucleophile to imines or iminium ions through Mannich-type reaction appears more useful (Scheme

C2-Alkylation of N-pyrimidylindole with vinylsilane via cobalt-catalyzed C–H bond activation

• Zhenhua Ding and
• Naohiko Yoshikai

Beilstein J. Org. Chem. 2012, 8, 1536–1542, doi:10.3762/bjoc.8.174

• as a directing group for rhodium-catalyzed C2-alkenylation [36], was entirely ineffective. Vinylsilanes bearing dimethylphenylsilyl and triphenylsilyl groups were amenable to the addition reaction with 1a, affording the adduct 3ab and 3ac in modest yields. Vinyltriethoxysilane also reacted with 1a in

Synthesis and evaluation of new guanidine-thiourea organocatalyst for the nitro-Michael reaction: Theoretical studies on mechanism and enantioselectivity

• Tatyana E. Shubina,
• Matthias Freund,
• Sebastian Schenker,
• Timothy Clark and
• Svetlana B. Tsogoeva

Beilstein J. Org. Chem. 2012, 8, 1485–1498, doi:10.3762/bjoc.8.168

• Organic Chemistry I, University of Erlangen-Nuremberg, Henkestraße 42, 91054, Erlangen, Germany 10.3762/bjoc.8.168 Abstract A new guanidine-thiourea organocatalyst has been developed and applied as bifunctional organocatalyst in the Michael addition reaction of diethyl malonate to trans-β-nitrostyrene

Organocatalytic asymmetric addition of malonates to unsaturated 1,4-diketones

• Sergei Žari,
• Tiiu Kailas,
• Marina Kudrjashova,
• Mario Öeren,
• Ivar Järving,
• Toomas Tamm,
• Margus Lopp and
• Tõnis Kanger

Beilstein J. Org. Chem. 2012, 8, 1452–1457, doi:10.3762/bjoc.8.165

• . Calculated (red) and experimental (blue) IR (A) and VCD spectrum (B) of compound (R)-3a. Screening of the catalysts for the asymmetric conjugated-addition reaction. Enantioselective addition of malonates 2a-2f to unsaturated 1,4-diketone 1a. Enantioselective addition of diethylmalonate 2a to substituted 1,4

Synthesis of compounds related to the anti-migraine drug eletriptan hydrobromide

• Suri Babu Madasu,
• Nagaji Ambabhai Vekariya,
• M. N. V. D. Hari Kiran,
• Badarinadh Gupta,
• Aminul Islam,
• Paul S. Douglas and
• Korupolu Raghu Babu

Beilstein J. Org. Chem. 2012, 8, 1400–1405, doi:10.3762/bjoc.8.162

• later stages is low. Impurity 2 was prepared by the dimerization of desacetyl-ensulfone derivative 13 using a strong base, such as sodium hydride, under Michael addition reaction conditions in an anhydrous medium (Scheme 2). This impurity can be controlled by using hydrous conditions during the

Enantioselective Michael addition of 2-hydroxy-1,4-naphthoquinones to nitroalkenes catalyzed by binaphthyl-derived organocatalysts

• Saet Byeol Woo and
• Dae Young Kim

Beilstein J. Org. Chem. 2012, 8, 699–704, doi:10.3762/bjoc.8.78

• effective (Table 1, entries 1 and 2), whereas the binaphthyl-modified, chiral, bifunctional organocatalysts III–VIII, bearing both central and axial chiral elements, effectively promoted the addition reaction in high yield, with high enantioselectivity (78–97% ee, Table 1, entries 3–8). Catalyst III gave

Efficient syntheses of 25,26-dihydrodictyostatin and 25,26-dihydro-6-epi-dictyostatin, two potent new microtubule-stabilizing agents

• María Jiménez,
• Wei Zhu,
• Andreas Vogt,
• Billy W. Day and
• Dennis P. Curran

Beilstein J. Org. Chem. 2011, 7, 1372–1378, doi:10.3762/bjoc.7.161

• amide 10 and alkyl iodide 11 afforded amide 12 in 95% yield. The chiral auxiliary was then removed with BH3·NH3 (92%) [34], then the resulting primary alcohol was oxidized under Swern conditions to provide aldehyde 13 (86%). A Marshall palladium-catalyzed addition reaction [35] between aldehyde 13 and

Synthesis, reactivity and biological activity of 5-alkoxymethyluracil analogues

• Lucie Brulikova and
• Jan Hlavac

Beilstein J. Org. Chem. 2011, 7, 678–698, doi:10.3762/bjoc.7.80

• the products 151–154 (Figure 9) were formed as by-products of the palladium catalyzed addition reaction of alkenes to C-5-mercuriated deoxyuridines. The synthesis of derivatives 151 and 152 started with condensation reactions of alkenes 155 and 156 with 5-chloromercuri-2'-deoxyuridine 4 in the

The arene–alkene photocycloaddition

• Ursula Streit and
• Christian G. Bochet

Beilstein J. Org. Chem. 2011, 7, 525–542, doi:10.3762/bjoc.7.61

• reaction mixture in a combined yield of 60%. The major meta product can be converted into the fenestrane by further irradiation (Scheme 18). This second [3 + 2] addition reaction can be accelerated by the addition of sensitizers and could be quenched with piperylene. The proposed mechanism involves a

Michael-type addition of azoles of broad-scale acidity to methyl acrylate

• Sławomir Boncel,
• Kinga Saletra,
• Barbara Hefczyc and
• Krzysztof Z. Walczak

Beilstein J. Org. Chem. 2011, 7, 173–178, doi:10.3762/bjoc.7.24

• and is used as a clinical regulator of the cardiac cycle [5]. Fluconazole (VI) 2-(2,4-difluorophenyl)-1,3-bis(1,2,4-triazol-1-yl)propan-2-ol is an antifungal drug used in the treatment and prevention of superficial and systemic fungal infections [6]. The base-catalysed Michael-type addition reaction

An easy assembled fluorescent sensor for dicarboxylates and acidic amino acids

• Xiao-bo Zhou,
• Yuk-Wang Yip,
• Wing-Hong Chan and
• Albert W. M. Lee

Beilstein J. Org. Chem. 2011, 7, 75–81, doi:10.3762/bjoc.7.11

• molecular platform via thiourea formation to give the key intermediate 4 in 70% yield. As a result of steric hindrance, an attempt to make the corresponding bis-thiourea adduct from 3 and 9-aminomethylanthracene was unsuccessful. However, 4 underwent a smooth addition reaction with the structurally less

Stereoselective synthesis of four possible isomers of streptopyrrolidine

• Debendra K. Mohapatra,
• Barla Thirupathi,
• Pragna P. Das and
• Jhillu S. Yadav

Beilstein J. Org. Chem. 2011, 7, 34–39, doi:10.3762/bjoc.7.6

• ) SnCl4, (1-ethoxyvinyloxy)trimethylsilane, CH2Cl2, −78 °C, 2 h, 70% (8a:8b = 3:7); (d) LDA, EtOAc, ZnBr2, −78 °C, 1 h, 82%, (8a:8b = 95:5). Reagents and conditions: (a) (1) TFA, CH2Cl2, rt, 4 h; (2) Zr(OtBu)4, HOAt, toluene, 60 °C, 12 h, 82% over two steps. Addition reaction under different conditions to

Formation of epoxide-amine oligo-adducts as OH-functionalized initiators for the ring-opening polymerization of ε-caprolactone

• Julia Theis and
• Helmut Ritter

Beilstein J. Org. Chem. 2010, 6, 938–944, doi:10.3762/bjoc.6.105

• , the addition polymerization of primary amines with diepoxides forming linear adducts has been intensively studied [21]. Linear epoxide-amine addition polymers can be obtained for instance by the addition reaction of diglycidyl ethers and aromatic primary amines in equimolar amounts. With regard to our

• reduced to the corresponding amine 3 via catalytic transfer hydrogenation. In presence of 1, a simultaneous addition reaction of the freshly formed amine groups took place (Scheme 1). The reaction was carried out using 4-methyl-1-cyclohexene as a source of hydrogen in bulk. To prevent overheating, the

• successful reduction of the nitroaromatic compound 2 was proven by IR spectroscopy by the disappearance of the asymmetric and symmetric NO2 stretching vibration absorption bands at 1589 and 1329 cm−1, respectively. The addition reaction of the new formed primary aromatic amine 3 with diepoxide 1 was proven

Concise methods for the synthesis of chiral polyoxazolines and their application in asymmetric hydrosilylation

• Wei Jie Li,
• Zun Le Xu and
• Sheng Xiang Qiu

Beilstein J. Org. Chem. 2010, 6, No. 29, doi:10.3762/bjoc.6.29

• catalytic activities and high enantioselectivities in various asymmetric reactions [14][15][16][17][18][19][20]. For example, chiral 1,2,2-tris[2-(4-isopropyloxazolinyl)]propane was shown to lead to high enantioselectivities in the Cu(II)-catalyzed asymmetric Michael addition reaction between indole and

Continuous flow enantioselective arylation of aldehydes with ArZnEt using triarylboroxins as the ultimate source of aryl groups

• Julien Rolland,
• Xacobe C. Cambeiro,
• Carles Rodríguez-Escrich and
• Miquel A. Pericàs

Beilstein J. Org. Chem. 2009, 5, No. 56, doi:10.3762/bjoc.5.56

• triethylboroxin mixture in toluene). Both flows were mixed in a T-shaped piece placed immediately before the reactor, in order to minimize the amount of background, non-enantioselective addition reaction before contact with the supported catalyst. Additionally, a supply of dry toluene was connected to both pumps

Efficient 1,4-addition of α-substituted fluoro(phenylsulfonyl)methane derivatives to α,β-unsaturated compounds

• G. K. Surya Prakash,
• Xiaoming Zhao,
• Sujith Chacko,
• Fang Wang,
• Habiba Vaghoo and
• George A. Olah

Beilstein J. Org. Chem. 2008, 4, No. 17, doi:10.3762/bjoc.4.17

• density on the fluorinated carbanion center, which makes the resulting nucleophile softer and more suitable for 1,4-addition with Michael acceptors. Hence, we explored the possibility of a base induced Michael addition reaction. Among the various bases and solvent combinations that we explored, the K2CO3